In an effort to measure the effects of bsa adsorption on pnc-Si, I made some samples from SC 073 (a good wafer for separations) and with the help of Graham Marsh (Waugh Lab), looked at them using AFM.  We did our first studies of the samples in water, just in case that drying somehow distorted…

In a previous post I showed that a colorimetric assay using sulfuric acid and phenol can be used to establish a linear relationship between known detergent concentrations and absorbance values. This assay proves helpful in the project related to Mark Dumont’s work in that it will allow detection of small quantities of detergents that pass…

This post is a follow-up to Professor McGrath’s post, “Permeabilities vs. pore sizes for ideal membranes.” In the aforementioned post, this equation is proposed: Ψ = Nπr2 Where Ψ is the porosity, N is the density of the pores, and r is the pore radius. Rearranging the above equation (assuming a constant porosity): Ψi =…

Last Friday, Chris and I met with Dave Glocker from Isoflux Inc., an expert in physcial vapor deposition.  Specifically, we wanted to get advice on the recent problems we’ve had with the AJA tool. Arcing from Lesker targets We recently decided to try new oxide targets from Lesker because the last batch of AJA targets…

After talking with Prahnesh, a graduate student in the Dumont Lab I obtained a protocol for a colorimetric assay used to detect the presence of detergents in solution. The assay uses phenol and concentrated sulfuric acid in the following manner: add 600uL Sulfuric Acid to 40uL of sample and vortex add 200uL 5% Phenol and…

Endotoxins (~10-1000kDa) are structural components of bacteria (LPS is the best known) that are released from bacteria when they die.  Endotoxins cause inflammatory responses in humans and animals (infections give you a fever) and in cultured cells.  For most cell culture applications, you don’t have to worry too much about endotoxins.  For monolayer permeability experiments,…

I’ve been growing brain endothelial cells on PET and pnc-Si membrane transwells for a variety of experiments, but mainly to measure the TEER (transendothelial electrical resistance).  TEER is used to track the integrity of cell monolayers grown on permeable supports.  As the monolayer gets ‘tighter’, the TEER increases.  PET membranes are marketed as transparent for…

I went through and characterized each wafer by thickness and RTP. I graphed “Average Pore Size vs. Porosity” and “Average Pore Size vs. Cut-Off Pore Size” for each processing condition that had at least four representative wafers. ** Yesterday, Professor McGrath and I had a quick chat about the data. I have inserted a few…

Here is the analysis of the wafers used in the pressurized gold separations: SC 199   Stat Result Mean Equiv Diameter 17.84 nm Median Diameter 18.30 nm Porosity 2.2% Weighted Mean Diameter 20.81 nm 90% Diameter 26.64 nm Roundness .782 Separates 10 nm from 15 nm w225   Stat Result Mean Equiv Diameter 18.33 nm…